Propelling system and method



June 23, 1925; 1,543,026

C. M. PAXTON PROPELLING SYSTEM AND METHOD Filed April 7. 1923 4 Shets-Sheet 1 INVENTOR ('lflford 1W. Iaxfon M ATTORNEY June 23; 1925. 1,543,026

c: M. PAXTQN PROPELLING SYSTEM AND METHOD Filed April '7. 1923 4 Sheets$heet 2 INVENTOR flyforg Jf. Paxton WATTORNEY June 23, 1925.

c". M. PAXTON PROPELLING SYSTEM AND METHOD Filed April 7, 1923 4 Sheets-Sheet 5 INVENTOR ['ljjfordjf. Parfazz M ATTORNEY June 23, 1925. 1,543,026

c. M. PAXTON PROPELLING SYSTEM AND METHOD Filed April 7. 1923 4 Sheets-Sheet 4 v I N V EN TOR @fi rd/mmm MA TTORNE Y Patented June 23, 1925.

UNITED STATES PATENT OFFICE.

CLIFFORD M. PAXTON, OF BROOKLYN, NEW YORK.

PROPELLING SYSTEM AND METHOD.

Application filed April 7,

- of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Pro elling Systems and Methods, of which the ollowin is a specification.

My present invention relates more par ticularly to marine propulsion, and though the invention is directly applicable to the propulsion of submarines, automotive torpedoes, and other wholly submerged bodies and though some of the principles are applicable to the propulsion of bodies in air, they are disclosed herein as applied to the specific purpose of propelling a vessel or ship of the displacement type floating on the surface.

For propelling suchvessels and ships I employ submerged Water jets, especially designed and arranged for the purpose of utilizing some effects which I have discovered can be developed by a high velocity jet stream, after it leaves the nozzle, particularly as concerns its effects upon the surrounding water and, through the intervention of such Water, upon the ships hull adjacent to which it is discharged. -My development and application ofthese effects are primarily directed toward reducing resistances and adverse pressures which normally oppose a moving ship; and toward accomplishment of this by causing the jet streams to induce augmented stream line in the water adjacent the ship, rearwardly from the normally high-pressure regions near the bow to lower pressure regions further aft.

The flow is induced conditioned and directed by the jet streams, it consists for the most part of outside water which is not actually taken into the propelling system, but is picked up by the jet streams after they leave the nozzles.

In making removal of resistances the primary consideration. I necessarily sacrifice propulsive thrust of the jets to a substantial degree; hence it will be evident that the superiority of mysystem, as compared with all prior systems. whether screw or jet, results from my employment of the discharged jet streams to such advantage in other ways as to more than compensate for because, though .ates and develops 1923. Serial No. 630,463

their comparative ineffectiveness as regards propulsive thrust.

My invention depends upon and includes many discoveries, investigations and experimental developments and I have found that l-Vith easily attainable high initial velocity, a submerged jet stream can be made to build up a cumulative stream having fivehun'dred or even a thousand times the crosssection of the initial stream.

The suction and flow-inducing effects are of useful intensity for high velocity removal of water from the entrance section of a propelled vessel only for a limited disstance backward from the nozzle. This useful excavating portion rapidly'decelerinto a transition portion throughout which excavation is unimportant, and this, in turn, develops into a characteristically different portion which is water-depositing and pressure-increasing. For convenience, I call this latter portion the plume.

Corresponding to these, the ordinary ship has first, the diverging entrance section with its bow-Wave and head pressure areas; then, further aft, there is a more or less parallel or neutral n'iidship section; then, a converging run section which is always a region of subnormal pressure, or suction, which is also adverse.

Taken in the above order, the above-described different qualities of the three successive portions of a high velocity jet stream exactly suit the different requirements of the three successive sections of the ship.

My invention involves lengthwise fitting of the respective jet stream portions to appropriate sections of the ships length, so as to produce streams of the required great cross-sectional area at midship, at the desired velocity, preferably by methods which permit of shortening the useful excavating portion of the stream to fit the entrance section, while maintaining sufficient initial cross-sectional area for suitably propelling the ship.

This may be accomplished by locating the nozzles substantially in advance of Where the maximum bow wave would normally tend to pile up and by suitably flattening or otherwise increasing the surface area relative to cross-section, as compared with a corresponding cylindrical stream. I also select a desired outward angle of discharge for decreasing skin-friction, fitting the jet streams to the ship, and for other effects, as will be explained below. When the entrance section has the jet streams thus fitted-to it, so that the useful water excavating energy has been concentrated along the entrance section, the transition portion will be thereby fitted to the midship section and in preferred models of hull the plume will naturally take effect under and along the run section.

The above and other features of my invention may be more'fully understood from the detailed description in connection with the diagrammatic illustration in the accompanying drawings, in whichi Fig. 1 is a top plan of a portion of a ships hull outline partly broken away to section on the line 1-1, Fig. 2.

Fig. 2 is an end elevation partly broken away to section on the line 2-2, Fig. 1.

Fig. 3 is an enlarged detailed section on the line 33, Fig. 2.

Fig. 1 is a composite, diagrammatic plan view of the outline of a ship indicating diagrammatically certain features of the flow of the water about the ship, the upper half indicating screw propulsion and the lower half propulsion by my method.

Fig. 5 is a side elevation of a hull corresponding to the lower half of Fig. 4, with the water surface diagrammatically indicated.

Fig. 6 is a diagrammatic plan outline similar to Fig. 1, but showing a modification.

Fig. 7 is a similar diagrammatic plan view showing another modification.

Fig. 8 is a side elevation of the entrance section of a ships hull showing another modification.

Figs. 9, 10 and 11 are respectively plan, side elevation and stern elevation of another modification.

These drawings are necessarily quite diagrammatic, particularly in the attempted illustration of water phenomena. B is the bow; S is the stern. The submerged body from B to M is the entrance section, and from M to S is the nun section.

The resistances offered by the water to the advance of'a hull forced through it, as by a screw 12, (Fig. 4:, upper half), include frictional resistance called skin friction, and the inertia resistances called water or residuary resistance. The latter includes the rearward pressure on the entrance section BM, which is set up when the forward surfaces start and accelerate flow of the inert water outward from to said surfaces as indicated by the arrows near B, Fig. 4. The water displaced is confined by the outlying mass water so that the pressure increases from the bow rearwardly but nonuniformly becoming an accentuated maximum somewhere about R, resulting in the well-known bow-wave, which breaks away from the hull as at G. Its crest is indicated by the line G, G, and the arrows in regions F and E indicate the flow with respect to said crest, the inwardly directed arrows E representing the subsurface movement.

Aft of the midship section there are hollows and subnormal pressures about the run MS due to hull suction or, more properly speaking, cavitation, into which water flows from regions H and J. The usual screw propeller would tend to ex cavate water from about the run, as indicated by arrows J, so that cavitation would be increased by excavation.

The above described inertia effects tend to create a rearward pressure differential.

While skin-friction increases in a ratio less than the square of the speed of the ship, the inertia resistances increase much more rapidly than skin friction. For instance, in the case of a given ship, the skin-friction may amount to or more of the total resistance at so-called low speed, while at higher speed the water resistance may become 70% or more of the total, notwithstanding the simultaneous increase in skinfrictional resistance.

While my invention involves modifying the effects of skin-friction as concerns resistance to the ship movement, it is primarily directed against said inertia resistances.

Referring to Figs. 1, 2, and 3 and the lower half of Fig. 4, it will be seen that the jet nozzle 1 is deeply submerged and discharges rearwardly. The initial jet stream water as widened by deceleration only is indicated by the lines a, a. The stream is confined by sharply defined walls of mass water so that all friction, cohesion and impact operate to pick up the water and carry it off as indicated by the lines 0, c, c, and b, b, 7). This ideal utilization of friction to remove water is an important feature of my invention. The removed Water is replaced by in-fiow at right angles to the jet stream surface as indicated by the short arrows at c, 0., and b, b, but a stream of easily obtainable, high velocity will excavate and carry off the water so rapidly that it produces a powerful suction effect as regards adjacent water and hull surfaces which are not beyond effective range. thereof. These subnormal pressures tend to take effect as surface depressions and where these are caused to develop about the entrance section of a moving boat, as shown in Figs. 5 and 8, there may be distinct hollows or depressions W at or near the place where the bowwave would otherwise be. The near surface water encountered by that part of the hull which is being pushed ahead of the nozzles, tends to flow parallel with the hullsurface into said depressions somewhat as indicated at B, Fig. 4. I

The jet stream is slowed dfiwn by the water it picks up until it ceases to be effec tively useful for water-excavating and beyond this point, indicated as at M in the drawings, the stream, being opposed by the relatively stationary mass water, naturally tends to set up sub-surface pressure, causing the stream to pile up or plume, as I call it. Thispart of the jet stream is caused to develop in the area P so that it flows about the aft or run section'of a moving ship into the subnormal pressure regions, where it may result in a wave of a sort heretofore unknown in the art. This may be called the run wave, and it may be somewhat as indicated at W", Figs. 5, 8 and 11. In many cases this )art of the stream will be so located and 0 such volume and velocity as to more than fill up the space the ship moves out of, thus resulting in a rearward trending wake, as at D. The above factors are variable, however, and even in a well designed system the trend may be somewhat forward instead of aft.

The flow-inducing portion of the stream may be shortened and its effects concentrated and confined to the dimensions of the desired region of the hull in any given case by increasing the surface area of the jet stream relatively to its cross section.

In the case of the jet streams indicated in the drawings, this development of surface has been accomplished after the manner indicated in Figs. 2 and 3, where the nozzle orifice is shown as a long narrow slot 6 extending nearly parallel with the hull surface 2, and in the present case extending along one-third or more of the surface approximately midway between the keel at A tirely surround the midship and the surface of the water W. This will give a stream which, when built up at top and bottom by induced flow can reach the surface and the keel, as indicated in Fig. 5, and, in combination with another similar jet on the other side of the ship, may ensection with a stream of rearwardly flowing water. The width of this slot has been carefully pro-v portioned to its length so that the jet stream will have its surface of contact with the outside water of such vlarge area-that its energy will be utilized and exhausted to the desired extent, in the high pressure region, before it passes the end of the entrance section at M. The principle is that a jet streamof given cross-section and veloc1ty has'the least possible surface area per unit length and its water-excavating portion will be of maximum length when the nozzle orifice is circular so as to make the stream cylindrical; but if the nozzle orifice be made long and narrow without substantially changingits outlet area, so that the jet stream will be a thin sheet having, per foot of length, ten times as much flow-inducing surface area, as the corresponding cylindrical stream its flow-inducing action will be concentrated so that the same total volume of water will be removed from a region onetenth as long, in one-tenth the time. This is of greatest importance because effectiveness in removing in'ertia pressures depends en.- tircly on rapid removal of the water as compared with the rate at which outside water can flow in in response to the suction or subnormal pressures created by such removal.

I have found that immediately outside the skin of a jet stream,'there is an area, or thin stratum, of negative pressure, the value of which maybe read upon a gauge attached to an impact tube. I have discovered by test that such negative pressure exists and results in a suction effect which I utilize as an effective propelling factor. This suction effect is normally equal on opposite faces of the jet stream, but by making the bow jet streams in the form of sheets dischar ed at aproper outward angle which, in t e case of Fig; 3, is about 14 degrees, the suction and pressure-reducing effect developed by the inner surface of the jet stream, as indicated by the arrows b, b,

will take effect on the, hull. This has the double advantage of using the water-excavating capacity of the inner face of the jet streamto carry away water as well as to maintaina'subnormal pressure area between the inside surface of the jet stream and the facilitating suitably restricted in-flow of outside water between the stream and the hull surface with less outward angle of projection for the stream.

To the extent that the hull of a ship is surrounded by the rearwardly flowing streams induced by my method, the surface is shielded from'impact of and normal fric tion' with the. mass water through which the hull is being propelled, and inertia and skinfrictional resistances are thereby respectively reduced and modified.

In Figs. 1, 2, and 3, 2 is the shell-plating of the ship, 1 is the nozzle, and 3 is the connection for a supply of Water under pressure. 4 is a plate, preferably though not necessarily, integral with the nozzle. 5 is a detachable mouth-piece in which is a suitable orifice 6. While this is shown as a slot, much the same effect may be procured from the use of a row or series of circular orifices, the streams from which would blend to form a sheet a short distance from the nozzle. The shellplating 2 may be cut away as at 7, to permit attaching the nozzles and permitting them to pass through the ships side. Similar construction has been employed for a wooden hull. Rivets, bolts, welds or other fastenings are assumed.

By having the nozzle tips readily detachable from the exterior of the ship, the oritice dimensions or angle of discharge may be easily altered; also renewals of mouth-pieces may be easily made as necessary. Screws or bolts for this purpose are indicated in Fig. 2. A In Fig. i the water is supplied to nozzle 1 at 3 by means of pipe 8 of a system con nected to a centrifugal, rotary or other suitable type of pump S), driven by a turbine, rotary engine or other suitable prime mover 10. The prime mover is shown as directly connected to the pump through shaft 10, but it will be obvious that gears may be interposed. In Fig. 5 is shown a desirable arrangement of the intake 11, aft of the nozzles and near the keel so that they will not be exposed in rough water.

The nozzles are located well forward preferably somewhere between one-fifth and one-third of the distance from the cutwater to the end of the entrance section, the main consideration being that they should be placed forward of the region of maximum adverse rearward pressure Where the bow-wave piles up just before leaving the ships surface.

Fig. 5 shows the hollows created by the jets on either side of the entrance and the wave running on either side of the run. Lines a and a have the same significance as in Fig. 1, while 6, e, and e; and (Z, (Z, and d, are analogous to b and 0 lines in previous figures and show that the jet builds up on top and bottom as well as along the sides. IV, IV, W and IV illustrate the approximate profile of the water line about the moving hull, contrasting with the straight broken line L which indicates the water line when the ship is stationary. IV is the hollow created by the excavation of water by the excavating portion of the jet streams, and IV shows the wave in the plume area that is, the water depositing effect of the jets. These might be canceled if the ship were propelled at higher speeds, if such speeds were gained by increasing propelling thrust without corresponding increase in watermoving power of the jets. The nozzle is directed so that normally the upper edge a, of the initial or high velocity part of the stream, is directed well below the normal surface level of the water. In the present case this requires a somewhat downward angle for the nozzle.

F-F is the so-called forefoot which is merely surface Water thrown up by the fully developed immediate prow entrance, and is not to be confused with the bowwave. 13 is the rudder, and steering can be greatly facilitated by hydraulic means not shown or claimed as a part of my invention. The intake 11, pump 9, service piping 8 and connection 3 to nozzle 1, respectively, may be the same as in Fig. 4.

Fig. 6 shows how a plurality of overlapping jets may be employed as whena widely variable speed range might be desirable. Variable speed through a considerable range is possible without the use of overlapping jets but a jet is more efficient at the speed for which it is designed, and it may be desirable to have two or more nozzles as 1*, 1", discharging separate streams, each properly fitted to the length of the hull, and either One or each of them designed to propel the ship at normal full speed when operating alone; then when both jets are turned on they can be made to deliver a correspondingly greater stream of water at less velocity, thereby increasing the proportion of the power applied as thrust. This is particularly useful for low speeds where inertia resistances are a small factor. More than two jets may be used, either separately or together, and fitting the hull either at the same speed or different speeds and when discharged either at the same Velocity or different Velocities. The space N is optional.

Fig. 6 also shows the combination of my system with a screw propeller 12'. Dotted line Q indicates the above-water outline of the hull of the ship at the stern. For such use in combination with a propeller, it seems preferable to employ high velocity jets of relatively small volume, more or less highly developed as to surface, to excavate water from about the entrance and move it aft, thus reducing the resistance to be overcome by the screw. Hence if my system is to be applied to a ship already equipped, a screw propeller of greater pitch might be required.

Fig. 7 illustrates the application of my system of propulsion to a ship having a considerable length of parallel body. 1" and I arethe nozzles for excavating water from about the entrance and filling in about the run, respectively. M and M indicate the parallel body. B and S are the bow and stern, respectively. The areas within the curved lines P and P are the respective plume areas. Ships with exceptionally bluff bows are apt to have a long parallel body so that short highly developed and high velocity jets may be used at the bow,

while parallel body jets operating at lower" velocity perhaps and at an angle far more efficient' than the bow-jets may be employed to afford the main propulsive effort.

Fig. 8 shows how horizontal subdivision .of the jet sheet is possible, in cases where a single sheet might have practical disadvantages; as where it is too broad to permit a sufficient volume of mass water to flow in behind it from top and bottom. This arrangement simply divides the sheet into two or any number of sheets, and allows space, illustrated by K, between the sheets for the inflow of mass water. 1 and 1 are the nozzles. B, M, W, W, W" and L have the same significance as in 'Fig. 5; asdo 7 also the short arrows and the lines leading from them. F-F is the forefoot, which is not to be confused with a fully developed bow-wave. The functioning will be clear from-explanations previously given. With this arrangement (as also that shown in F i 6);the sheets combine to form. a single stream at no great distance from the nozzle orifice. One of the streams may be shut off without seriously modifying the action of.

the other. F or-instance, the top stream might be shut off to save power when the ship is running light and floats high in the water, or for other reasons.

The following facts and figures, ascertained by actual tests, prove the existence of the various above-described phenomena. In the case of a reduced size destroyer, built and tested by me, which was 34.5 feet in length and duplicated proportionately as nearly as practicable,- the under-water lines of a full-size destroyer, I found that with 110 pounds pressure and total effective orifice area of .85 of a square inch, the boat was propelled at' 9.3 .knots speed; when towed at speed taken to be the same, the tow-line resistance was 240 pounds. lVhen the boat was held stationary by a long stern line tied to a dynamometer on the dock, so that removal of inertia resistance had no value whatever, the pull exerted by the jet streams was 215 pounds. This pull exceeded the calculated nozzle reaction, and suction at the intakes, by 53.13 pounds. Hence the 53.13 pounds of excess thrust was taken to be the value of the above described suction effect of the jet streams on. the adjacent hull surfaces.

When the boat was being propelled by my system at said 9.3 knots speed, he propelling effort due to nozzle reaction (reduced tow-line resistance must be accounted for was calculated to body section.

114.73 pounds, 44.74 was calculated to be due to the above described suction effect of the jet streams on theadjacent hull surfaces (reduced by the boats movement) and 69.99 bedue to reduction of resistance. v f

To propel the same boat at 9.3 knots speed with a screw propeller required an 18 by 24 inch, three-blade propeller, at 700 .r. p. m., which, at the dock, pulled 5-10 pounds on a stern line. Hence, my system, pulling but 215 pounds at the dock with 161.87 pounds of nozzle reaction and suction, propelled the boat at the same speed as a screw propeller pulling 510 pounds under similar conditions.

With the boat held stationary, it was ascertained that the approximate cross-sectional area of the cumulative stream induced by the jets in full operation and flowing sternward past the midship, was from 1400 to 1.500 times the total effective orifice area of said jets.

An outward angle of discharge of 14 degrees from the hull surface at the nozzle locations, and approximately 30 degrees to the fore and aft center line of the ship, was satisfactory.

Calculations of resistance by the law of comparison. for a full-size-destroyer at the corresponding speed and calculations covering the application of my system, deduced from the operation of my model, indicate that the full-sizedestroyer, if propelled at the corresponding speed by my method, [would require 35.5% less power than is now necessary for its propulsion by twin screws,

In practice the concrete result in view is the production of a cumulative rearwardly flowing stream or sheath of water, the cross sectional area of which at the end of the entrance section, when the ship is running at speed, is approximately the same as the niilaximum under-water cross section of the s 1p.

While my system is applicable for almost any vessel of the displacement type having to utilize the advantages of my system. A

" hull illustrating certain features of adaptation is shown in Figs. 9, 10, and 11. Fig. 9 is a plan outline of the hull just above the turn of the bilge about on the line 9 9, Figs. 10 and 11. j The entrance section from B to M is approximately one-third the length of the boat. Actually the maximum cross section is slightly aft of M, but between M and M the curvature is so slight that its effect does not differ much from that of a parallel Hence we have from M to S independently of the propulsive effect of ,asection approximately twice as long as the i effective entrance section, giving much greater opportunity for the sheath stream to decelerate and plume effectively within the long area P. This permits of much higher midship velocity for the cumulative jet stream at M, without sacrificing effective development of plume pressures and filling in of hollows about the run section.

Fig. 11 is a rear view showing the midship outline M, the stern outline S, and a characteristic intermediate section SM, indicating through what a long distance and at what effective angles the plume may develop and apply helpful pressures about the run.

Other minor but useful features are the header 8 extending through the bow of the ship which supplies the jets l 1 and which is supplied by the pumps, not shown, through conduit 8*. Another point is the location of the intake 11 which is in the bottom of the ship not far forward of the mid ship section, where it will always be submerged in solid water even in the roughest weather. This is important because while nozzle reaction of the jets and the consequent load on the pump and engine are approximately constant, regardless of whether the jets come out of the water or not, exposure of the intake and suction of air therethrough would cause the propelling thrust to fail and the engine to race, both of which would be very objectionable from the viewpoint of practical utility.

In these figures the water line W, W, forefoot F-F, hollow W, runwave W, and jet stream lines have the same significance as in the preceding figures.

So far as concerns the basic principles of my method, it will be evident that these may be utilized even more consistently under a wider range of conditions if the nozzles are adjustable while running, as to area or contour or angle or all three.

I have described and illustrated with considerable particularity various of the resistance removing and propulsive factors that may be involved in the practice of my pres ent invention, but it will be understood that the experimentaldata and calculations are for illustrative purposes and that my broad principle of fitting the different characteristic portions of the jet to the appropriate characteristic sections of the ship can be applied in practice without reference to any such data and without reference to the theories which I have advanced as reasonably accounting for the remarkable results achieved.

While all of the embodiments shown in the drawings are covered by the broad claims hereinafter set forth, it will be noted that various modifications of the method as well as some specific details of construction are specifically patentable over the primary illustrative form on which the broad claims are based, and these specifically patentable features are reserved for divisional applications about to be filed by me.

While some of the fundamental principles of my invention are capable of application to air jet propulsion of bodies submerged in air, it will be evident that the application of said principles will require material modifications because of the materially different functioning of both the jet stream and the resistance medium by reason of the fact that air is easily expansible and compressible, has little Weight, inertia, or momentum, and no cohesion, surface tension or viscosity; all

contrasting with water which is perfectly in expansible and incompressible; has great weight, inertia, and momentum; and has 'marked cohesion, surface tension and viscosity.

I claim:

1. A marine vessel of the displacement type, in combination. with propulsion means, including means for supplying water at relatively high pressure and submerged noz zles designed and arranged to project said water as substantially rearwardly directed water-jets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being so directed as to discharge said water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, and initial jet velocity, being predetermined and corelated with reference to the size and the desired speed of the vessel, so as to keep the high velocity initial portion of the jet stream from immediate bending to the hull surfaces, and so as to restrict theuseful water-excavating, pressure-reducing portions of the resultant streams substantially to the regions adjacent the entrance, section of the vessel; to restrict the transition portions of said streams substantially to the regions adjacent the, surfaces of the vessel amidship; and to restrict the water-depositing, pressure-increasing portions of said streams substantially to the regions adjacent the surfaces of the vessel aft of the after end of the entrance section or adjacent the run section, substantially as and for the purposes described.

2. A marine vessel of the displacement type, in combination with propulsion means. including means for supplying water at relatively high pressure andsubmerged nozzles designed and arranged to project said water as substantially rearwardly directed Water-jets having correspondingly high initial. velocity, said nozzles being located near the hull surfaces substantially aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the eutrance section of the vessel, and being so directed as to discharge said water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, and initial 'et velocity, being predetermined and corelated with reference to the form, size and desired speed of the vessel, so as to restrict the useful water-excavating, pressure-reducing portions of the resultant streams substantially to the regions adjacent the entrance section of the vessel, substantially as and for the purposes described.

A marine vessel of the displacement type, in combination with propulsion means, including means for supplying water at relatively high pressure and submerged nozzles designed and arranged to pro ect said water as substantially rearwardly directed water-jets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being so directed as to discharge said, water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the, contours and areas of nozzle orifices, and initial jet velocity, being predetermined and corelated with reference to the size and the desired speed of the vessel, so as to permit water to flow into the space between the initial jet stream and the hull surfacev and so as to restrict the useful water-excavating, pressure-reducing portions of the resultant streams substantially to the regions adjacent the entrance section of the vessel, and to restrict the water-depositing, pressure-increasing portions of the resultant streams substantially to the regions adjacent the surfaces of the vessel aft of the after end of the entrance section, substantially as and for the purposes described.

4. A marine vessel of the displacement type, in combination with propulsion means, including means for supplyirg water at relatively high presure and submerged nozzles designed and arranged to project said water;

as substantially rearwardly directed waterjets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being sodirected as to discharge said water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, and initial jet velocity, being predetermined and corelated with reference to the size and the desired speed of the vessel, so as to restrict the useful waterexcavating, pressure-reducing portions of the resultant streams substantially to the regions adjacent the entrance section of the vessel and to restrict the water-depositing, pressure-increasing portions of the resultant streams substantially to the regions adjacent the surfaces of the run section of the vessel, substantially as and forthepurposes de scribed.

. 5. A marine vessel of the displacement type, in combination withpropulsion means,

includin means for sn 1 in Water at rel- 8! PP dy g atively high pressure an submerged noz-' zles designed and arranged to pro ect, said water as substantially rearwardly directed water-jets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being so directed as to discharge said wa erjets at a sub stantial angle outwardly with'respect to the adjacent hull surfaces near the nozzles; the

outward angles offdischarge, the contours and-areas of nozzle orifices,and initial jet velocity, being predetermined and corelated with reference to the size and the desired speed of the Vessel, so as'to restrict the useful water-excavating, pressure-reducing portions of the resultant streams substantially to the regions adjacent the entrance section of the vessel and to restrict the transition portions of said streams substantially to'the regions adjacent the surfaces of the Vessel amidship, substantially as and for the purposes described. I

-6. A marine vessel of the displacement type, in combination with propulsion means, including means for supplying water at relatively high pressure and submerged nozzles designed and arranged to project said water as substantially rearwardlydirected waterjcts having correspondingly high initial velocity, said nozzles being located near the -'hull surfaces aft of the stem but inadvance of the regions of normal maximum high pressure which are'adjacent the forwardly directed surfaces of the entrance sectionof the vessel, and being so directed as to discharge said water-jet at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, being-predetermined and corelated with reference to the size and the desired speed of the vessel, so that the initial jet streams are and initial jet velocity, v

projected through the regions or normal maximum high pressure which are adj acent and for the purposes described.

7. A marine vessel of the displacement type, in combination with propulsion means,

including means for supplying water at relatively high pressure and submerged nozzles designed and arranged to project said water as substantially "rearwardly directed waterjets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being so directed as to discharge said water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, and initial jet velocity, being predetermined and corelated with reference to the size and the desired speed of the vessel, and the jet streams being pro: jected through the regions of normal maximum high pressure which are adjacent the forwardly presented surfaces of the entrance section of the vessel, so that said jet streams induce relatively large volume flow of adjacent mass water rearwardly to normal low pressure regions which are adjacent the surfaces of the vessel aft of the entrance section, substantially as and for the purposes described.

8. A marine vessel of the displacement type, in combination with propulsion means, including means for supplying water at relatively high pressure and submerged nozzles designed and arranged to project said Water as substantially rearwardly directed water-jets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being so directed .as to discharge said water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, and initial jet velocity, being predetermined and corelated with reference to the size and the desired speed of the vessel, so that the jet streams are projected through the regions of normal maximum high pressure adjacent the forwardly presented surfaces of the entrance section of the vessel and so that the cumulative jet streams, including the initial streams and the relatively large volume flow of adjacent mass water induced thereby, have a cross-sectional area at 'the end of the entrance section, which exceeds the maximum cross-sectional area of the submerged portion of the vessel, and a rearward velocit less than the forward speed ofthe vesse, substantially as and for the purposes described.

9. A marine vessel of the displacement type, in combination with propulsion means, including meansfor supplying water at relatively high pressure and submerged nozzles designed and arranged to project said Water as substantially rearwardly directed water-jets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being so directed as to discharge said water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, and initial jet velocity, being predetermined andcorelated with reference to the size and the desired speed of the vessel,so that the jet streams are projected through the regions of normal maximum high pressure adjacent the forwardly presented surfaces of the en trance section, and so that the cross-sectional area of the cumulative streams at the end of the entrance section exceeds the maximum cross-sectional area of the submer ed portion of the vessel, and so that, amids ip, said cumulative rearwardly flowing streams constitute a sheath substantially surrounding the submerged portion of the hull, substantially as and for the purposes described.

10. A marine vessel of the displacement type, in combination with propulsion means, including means for supplying water at relatively high pressure and submerged nozzles designed and arranged to project said water as substantially rearwardly directed waterjets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the vessel, and being so directed as to discharge said water-jets at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the outward angles of discharge, the contours and areas of nozzle orifices, and initial jet velocity, being predetermined and corelated with ref erence to the size and the desired speed of the vessel, so that the jet streams are projected through the regions of normal maximum high pressure adjacent the forwardly presented surfaces of the entrance section of the vessel so as to induce relatively large volume flow of adjacent mass water rearwardl from said regions of normal maximum 'igh pressure, the offset and outward angle of discharge being such as to allow suitable space between the jet and the ships surface at point of discharge, so that said high velocity jet streams do not contact with the surfaces of the vessel, but by the combined effect of excavation of Water between the jet stream and the ships. surface, the increment in said streams due to induced flow of adjacent mass water, and the forward movement of the vessel, the cumulative streams are brought substantially intocontact with the hull surfaces at or near the after end of the entrance section of ,the vessel, substantially as and for the purposes described.

11. A marine vessel of the displacement type, in combination with propulsion means, including means for supplying water at relatively high pressure and submerged nozzles designed and arranged to project said water as substantially rearwardly directed water-jets having correspondingly high initial velocity, said nozzles being located near the hull surfaces aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the orwardly directed surfaces of the entrance section of thevessel, and being sodirecwd as to discharge said water-jets .at a substantial angle outwardly with respect to the adjacent hull surfaces near the nozzles; the

contours and areas of nozzle orifices, and

initial jet velocity, being predetermined and corelated with reference to the size and the desired speed of the vessel, whereby the entire power; for propulsion of the vessel is primarily applied and exerted through and by means of the streams of water projected from said nozzles, substantiallyas and for the purposes described.

12. The method ofpropelling a ship.

' through the water and at the same time sub-p stantially preventing the formation of bowwaves' and of forward-trending wake, which method consists in discharging j et 'streams from nozzles located aft of the stem but in advance f-the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the shi said stream having relatively small vo umc and high velocity and being directed outwardly and rearwardly from said nozzles through said regions of normally maximum high pressures; the outward angles of discharge, areas of nozzle orifices and the initial jet velocity being predetermined and co-related so as to transfer around the midship of the the contours and vessel by induced flow, a volume of water aft of the stem but in advance of the regions of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the Vessel, and discharging relatively high velocity water jet streams at an outward angle to the hull and rearwardly from said nozzles, through said regions of normal maximum high pressure; the contours and areas of nozzle orifices, and initial jet velocity, being predeterminedand co-related so as to transfer around the midshipof the vessel by induced flow, a volume of mass water at least equal to the volume that would normally be displaced by the ship in its movement, said volume of mass water transferred locatingnozzles near the hull surfaces of the vessel,-

by induced flow with respect to the moving ship being approxlmately one hundred or more times the volume of water discharged from said nozzles, substantially as and for the purposes described.

14. The method of propelling a ship through the water, which method consists i in discharging high velocity submerged water-jet streams outwardly and rearwardly from nozzles located aft of the stem but in advance of the regions'of normal maximum high pressure which are adjacent the forwardly directed surfaces of the entrance section of the ship, and at the same time limiting the effective water-excavatin portions of said jet streams to regions su stantially adjacent the forwardly prwented surfaces of the entrance section, by discharging said jet streams from relatively lon and narrow orifices, thus giving to sai streams relatively large surface area in respect to volume; said streams section and surface area predetermined with respect to the size, form and speed of the ship and the initial velocity of the 'ets, so as to restrict the length of the usefu or effective water-excavating portions of the streams substantially to said regions.

Signed at New York in the county of New York and State of N ew York, this sixth day of April, A. D. 1923.

CLIFFORD M. PAXTON.

having cross. 

